1. Field of the Invention
The present invention relates to a method of manufacturing a circuit device, and more particularly relates to a method of manufacturing a circuit device including leads which function as external terminals.
2. Description of the Related Art
With reference to FIG. 5, a configuration of a conventional hybrid integrated circuit device 100 will be described. This technology is described for instance in Japanese Patent Application No. Hei 5 (1993)-102645. Conductive patterns 103 are formed on a surface of a rectangular substrate 101 with an insulating layer 102 interposed therebetween. Each of circuit elements is fixed to a desired spot in a corresponding one of the conductive patterns 103 to form a predetermined electric circuit. Here, as the circuit elements, a semiconductor element 105A and a chip element 105B are respectively connected to the conductive patterns 103. Each of leads 104 is connected to a corresponding one of pads 109, which are formed in a peripheral portion of the substrate 101, and which are respectively made of the conductive patterns 103, and functions as an external terminal. A sealing resin 108 has a function of sealing the electric circuit formed on the surface of the substrate 101. The hybrid integrated circuit device 100 thus configured makes it possible to actively release heat generated from the semiconductor element 105A and the like to the outside through the substrate 101. Thus, the device has excellent heat release properties.
The hybrid integrated circuit device 100 described above is manufactured in the following manner. First, the conductive patterns 103 are patterned on the surface of the substrate 101 made of metal such as aluminum. Next, the semiconductor element 105A and the chip element 105B are fixed, and electrically connected, respectively to predetermined spots in the conductive patterns 103. Furthermore, the leads 104 are fixed to the respective pads 109 each made of the conductive pattern 103. Lastly, the sealing resin 108 is formed on the surface of the substrate 101 in a manner that the circuit elements including the semiconductor element 105A and the like are covered with the sealing resin 108.
However, the above method of manufacturing a hybrid integrated circuit device has a problem that positioning of the leads 104 is troublesome.
Specifically, details of the step of fixing the leads 104 are as follows. First, a jointing material such as solder is applied onto a surface of each of the pads 109 formed on the surface of the substrate 101. Next, a position of a tip of each of the leads 104 is aligned with the surface of a corresponding one of the pads 109. Furthermore, the solder on each of the pads 109 is melted by use of a reflow furnace or the like, and thus the leads 104 are fixed to the respective pads 109.
Accordingly, in the above step, it is necessary to position the tip of each of the leads 104 to the top of a corresponding one of the pads 109, and to hold the lead 104 at a predetermined position until the solder is melted and solidified. As a result, it takes a lot of trouble to fix the leads 104.
By using a lead frame having a plurality of leads 104 connected thereto, the leads 104 can be collectively positioned thereto. Thus, the positioning of the leads 104 can be facilitated. However, even in a case where the lead frame is used, the lead frame is required to be positioned to the substrate, and equivalent work is required to be done. For this reason, it is expensive to position the leads 104.